[WIP] Docs for Sage 9

[retlehs]

post-launch

• rename 'theme wrapper' to 'blade templates', setup 301

Sage uses [Laravel's Blade](https://laravel.com/docs/5.5/blade) templating engine.

## Passing data to templates

Sage includes a `sage/template/{$class}/data` filter that can be used to pass data to templates. This is the most simple way to pass data.

```php
add_filter('sage/template/page/data', function (array $data) {
    $data['header_image'] = get_field('header_image');
    $data['header_content'] = get_field('header_content');
    return $data;
});

In your Blade templates for pages you can now use {{ $header_image }} and {{ $header_content }} to output the data.

Controller for Sage 9, written by Darren Jacoby, offers another method for passing data to templates. The Controller plugin works off of files in the app/controllers/ directory.

[Log1x]

Thought I'd throw it here rather than an issue (hope that's ok)--

https://github.com/roots/docs/blob/sage-9/sage/theme-development-and-building.md

To clear up confusion, when adding third party packages you omit the extension.

So import 'slick-carousel/slick/slick.min.js'; becomes import 'slick-carousel/slick/slick.min'; -- Just ran into this issue when beginning to convert my theme from Sage 8.5 to Sage 9.

Feel free to delete this post once acknowledged.